When You Place A Dispenser Facing Downwards Or Upwards And Place TNT Inside, Powering The Dispenser Will Dispense TNT But The TNT Will Not Make A Fuse Noise.
How To Reproduce:
1. Place Dispenser Facing Up Or Down
2. Place TNT Inside Dispenser
3. Power Dispenser
This might actually happen when the dispenser is facing any direction, i never tested that.